The present invention relates to control valves for controlling flow of fluids and, in particular, it concerns a control valve in which a valve seat and a plurality of plug guides are integrated as parts of a guide-and-seat insert.
Fluid flow control valves are often implemented with a valve seat which is manufactured separately from the main valve body and subsequently attached to the body. This allows the valve seat to be manufactured from material which has a higher resistance to abrasion than the main body of the valve, and also allows for replacement of the valve seat in case it becomes worn during use.
In certain valves, access to the valve seat itself may be awkward. In such cases, attachment or replacement of the valve seat may be problematic.
Particularly, although not exclusively, in large valves used with high-volume liquid flow, the forces exerted on the valve plug by drag of liquid flowing through the valve cause rapid wear on arrangements of linear bearings used to support the plug along its range of motion. In most cases, the plug is supported by one or two linear bearings deployed coaxially along an axis of symmetry of the plug. Such support structures are mechanically far from ideal.
There is therefore a need for a control valve structure which would allow installation or replacement of a valve seat without requiring direct manual access to the valve seat itself and which would provide enhanced mechanical support for the valve plug, without complicating the structure or maintenance of the control valve.